In current new drug development, it is necessary to discover the toxicity caused by a drug at an early stage. One known example of this toxicity is drug-induced (acquired) QT prolongation syndrome, which is a disease that causes severe arrhythmia in a patient.
Drug-induced QT prolongation syndrome is a serious disease with which QT interval prolongation appears on an electrocardiogram after drug administration, and ventricular fibrillation often occurs after TdP (Torsades de pointes: non-sustained polymorphic ventricular tachycartha), resulting in syncope or sudden death. In fact, out of the 25 drugs whose sales were stopped in the US market after 1980, five drugs have been determined as causing drug-induced QT prolongation syndrome.
In this regard, to discover toxicity that is caused by a drug, non-patent literature 1 discloses a measurement method in which the effect of a drug on the activity of an ion channel is analyzed based on the change in the electric potential of a cell in a drug-administered culture solution. This measurement method is carried out once a cellular electric potential measuring container is mounted on an electric potential measuring device. This cellular electric potential measuring container includes a plurality of wells for accommodating a culture solution and cells, and a measurement electrode and a reference electrode are disposed on the bottom of each well.
However, with the foregoing measurement system, cells to be measured may weaken or die, sometimes making it impossible to precisely measure cellular electric potential.